The present invention is related to the preparation of 3-carboalkoxypyrrolidones.
The compounds to be synthesized 3-carboalkoypyrrolidones of the formula ##STR1## are useful as intermediates in the preparation of certain pesticides, and more particularly of certain herbicides.
Prior to the present invention, the primary method for synthesizing pyrrolidones used the reduction of a nitro group to an amine to form the 1,2-bond of the pyrrolidone ring. This method precludes the formation of a pyrrolidone ring in which the nitrogen atom is substituted with anything other than hydrogen. To substitute the nitrogen after the ring has been formed involves forcing conditions and the problem that the 3-position of the ring is more reactive.
A process has been described (Japanese publication JP 46/24381: CA 75(23):140709m) that allows for the introduction of a variety of substituents on the nitrogen. but it also results in mixtures of two different ring systems. In addition, to be useful as herbicide intermediates, the pyrrolidones that are formed must have the methylene group at the 3-position oxidized to a carboxylic acid and the carboxylic acid at the 4-position reduced to an alkyl group, a difficult and time-consuming procedure.